On the Forehand, I think describing it as pulling up and across could help some people, who don't understand phrases like rotate into contact, rotate your core use your core, etc etc. One the one handed backhand it's a horrible description and is confusing a lot of beginners on the forum.

On the forehand I prefer to think of the stroke as coiling early and then rotating back into the stroke, while I extend my arm forward and through. I hit with a modern stroke with plenty of topspin.

Since Wegner tells people not to prep early or worry about early prep, his approach of just telling students to pull up and across isn't going to work for every student, because in order to uncoil dramatically like in the modern strokes, you have to be coiled in the first place!

If that approach works for you fine, but most accomplished coaches don't teach it that way.

You should give Oscar's method a try at least and report back with how you felt about it.
I think Oscar's method works especially well for beginners because it doesn't clutter their mind with a thousand different things to remember.